With reference initially being made to FIGS. 5-7 of the drawings, a conventional strap binding method, and the apparatus operatively provided for carrying out the method, for binding articles to be bound by means of an encircling tensioned steel band or strap, will first be described in order to provide a brief descriptive foundation of typical binding methods and apparatus normally employed within the above-identified technological field in connection with which the present invention comprises improvements thereover.
As can best be appreciated from FIG. 5, a conventional binding apparatus includes a multi-functional binding head 1 which is vertically movable with respect to a support frame, not shown, of the apparatus. Articles 2 to be bound by means of an encircling binding strap 3 are conveyed to a predetermined position beneath the binding head 1. The binding strap 3, which is, for example, a steel band, is fed from a suitable dispenser or supply means, not shown, by means of a forward rotational drive operation of reversible-feed rollers 4 which are also disposed within the binding head 1. The strap 3 is guided around the articles 2 to be bound through means of a chute and a gate, both not shown, and after encircling the articles 2 to be bound, the leading end 3a of the strap 3 re-enters the binding head 1 in preparation for a bonding operation with respect to the succeeding or trailing end portion 3b of the strap 3 whereby the encircling band or strap can be properly tensioned and secured about the article 2 being bound.
More particularly, when the leading end portion 3a of the strap 3 re-enters the binding head 1 and is disposed beneath the succeeding or trailing end portion 3b of the strap 3 as illustrated in FIG. 6(a), a stationary cutter 5 and a jaw 6, which is movable relative to stationary cutter 5, are closed with respect to each other so as to intermesh with each other and thereby securely grip an upstream portion of the leading end portion 3a of the strap 3. When the leading end portion 3a of the strap 3 is therefore securely gripped, the drive rollers 4 are rotated in their reverse mode so as to thereby take-up or retract the residual or trailing end portion 3b of the strap 3. As a result of such reverse rotation or retraction operation performed upon the trailing end portion 3b of the strap 3, the latter is effectively removed from the chute and gate, not shown, such that the article 2 to be bound has the binding strap 3 tightened thereabout. At the same time, the binding head 1 is lowered onto, or into engagement with, the article 2 to be bound a illustrated by means of the arrow d shown in FIG. 1.
While increased tension is being applied to the binding strap 3 by means of the high-torque reverse rotation of the drive rollers 4, a sealing fitment or crimped ferrule is secured upon the overlapped portions of the leading end portion 3a of the strap 3 and the trailing end portion 3b of the strap 3 as shown at 7 in FIGS. 6 and 7. The aforenoted crimping operation is achieved by means of the relative cooperation defined between jaw 6 and vertically movable notchers or crimping mechanisms 9. As can be readily appreciated from FIGS. 6(a) and 6(b), the crimping mechanisms 9 comprise downwardly extending prongs, teeth, or blade members which are laterally spaced with respect to each other so as to correspond with similarly laterally spaced upstanding portions of jaw 6 whereby when the crimping mechanisms 9 and jaw 6 relatively approach each other, as a result of lowered movement of the mechanisms 9, the ferrule 7 will be crimped in an undulated or corrugated manner which, more particularly, define notched portions 10 upon the ferrule 7 as best seen in FIG. 7. These crimped or notched sections of the ferrule 7 are then calked such that the overlapped strap portions of leading end portion 3a and trailing end portion 3b of strap 3 are effectively bonded to each other. At the same time, the bonded strap portions are severed and separated with respect to the residual supply portion 3c of the strap 3 by means of stationary cutter 5 which operatively cooperates with a vertically movable cutter 11.
It is further noted that when the jaw 6, which serves as an underlay or underlying foundation for supporting the overlapped portions 3a and 3b of the strap 3, and the ferrule 7 disposed thereabout, so as to operatively cooperate with the crimping mechanisms 9, is transversely removed from its operative disposition relative to crimping mechanisms 9, the bonded strap 3 resiliently achieves a predetermined amount of looseness or slack generated as a result of such removal or withdrawal of the jaw 6. However, a sufficiently high amount of tension has in fact been imparted to the binding strap 3, by means of the high torque reversely driven rollers 4, and fixed therein by means of the aforenoted bonding process, that such predetermined amount of looseness or slack does not adversely or deleteriously affect the binding state of the strap 3 about article 2.
As set forth hereinabove, the conventional strap binding operation and apparatus has been described in accordance with the most commonly prevailing example or embodiment, however, the bonding means comprises a variety of different examples. For example, the overlapping strap portions may be bonded to each other by means other than the aforenoted seal fitment or crimped ferrule, such as, for example, by means of spot welding or similar techniques. Furthermore, the gripping means comprising stationary cutter 5 and movable jaw 6, as shown in FIG. 6(a), wherein the cutter 5 and jaw 6 define a single-planar or single-edge gripping means, may alternatively comprise multi-edge or multi-planar gripping means, such as, for example, disclosed in FIG. 6(b). More particularly, the binding strap 3 has a portion thereof disposed upstream of the leading end 3a thereof sandwiched between and gripped by means of a sawtooth holding surface 5s of stationary cutter 5 which operatively cooperates with a flat surface portion 8 of the movable jaw 6.
Regardless of the particular type gripping means and/or bonding means or technique employed in connection with the strap binding process conventionally performed, the binding process always includes the basic serial steps of encircling the articles 2 to be bound by means of the binding strap 3; gripping the leading portion 3a of the binding strap once the strap has completely encircled the article 2 to be bound; taking up the trailing end portion 3b or the residual portion 3c of the binding strap by means of reverse rotation of the driving rollers 4; further tightening and tensioning of the binding strap by rotating the driving rollers 4 in their reverse mode under high-torque conditions; bonding the overlapping leading end and trailing end portions 3a and 3b of the strap 3 to each other under such tensioned conditions; cutting and separating the bonded strap 3 from the residual strap portion 3c; and removing the underlay 6.
In view of the foregoing, it is appreciated that in order to properly perform a strap binding operation, it is necessary to securely grip the leading end portion 3a of the strap 3 between the stationary cutter 5 and the jaw 6 so as to permit the same to assuredly resist or withstand the high tension imparted to the trailing end portion 3b of the strap 3 by means of the drive rollers 4 being driven in their reverse mode under high-torque conditions. In addition, it is also to be appreciated that even after the residual portion 3c of the binding strap 3 has been severed and separated from the trailing end portion 3b, or more particularly, from the bonded leading and trailing end portions 3a and 3b, the high degree of tension still remaining within the bound binding strap 3 still acts upon or is present within all portions of the bound binding strap 3. In particular, such high degree of tension acts upon a critical portion of the bound binding strap 3 which is defined between the bonding fitment 7 and the previously gripped portion of the strap 3 located upstream of the bonded section comprising overlapped strap portions 3a and 3b. Accordingly, the steel band strap 3 employed for such binding operations has sufficient tensile strength which is capable of adequately resisting such high degree of tension imparted thereto. For example, a conventionally used steel band strap may have a width dimension of 0.75-1.25 inches (19-32 mm), a thickness of 1 mm or less, and a tensile strength of approximately 75-100 kgs/mm.sup.2.
Nevertheless, the strong aforenoted intermeshing gripping action defined between the stationary cutter 5 and the jaw 6 has its negative aspects in view of the fact that such gripping operation produces scars or grip marks upon the leading end portion 3a of the binding strap 3. For example, FIG. 7(a) shows a grip mark 12s which is produced by means of the ingle-gripping structure of FIG. 6(a), while FIG. 7(b) discloses grip marks 12m which are produced by means of the multiple gripping structure of FIG. 6(b).
Still further, if the gripping force achieved by the gripping means of either FIGS. 6(a) or 6(b) is less than the tightening tension applied to the strap 3 by means of the reversely driven driving rollers 4, the strap 3 will tend to slip within the gripped region thereof whereby the strap will experience cutting or tearing by means of the gripping means illustrated in either FIGS. 6(a) or 6(b). In addition, the residual binding tension will be substantially reduced.
Still yet further, in considering the single-gripping means of FIG. 6(a), it is appreciated that the single grip mark 12s is relatively large and deep. Accordingly, if an excessive amount of tension is applied to the binding strap so as to enhance the binding force thereof, the strap 3 may tear or be cut by the gripping means within the vicinity of the grip mark region thereof. In addition, due to the large size of the grip mark scar, there is an increased risk or possibility that the strap will be broken or partially torn if, for example, a bending force, or an external force in the shearing direction, is applied to the binding strap during, for example, transportation of the bound articles.
In a similar manner, considering the multiple-gripping means of FIG. 6(b), the gripping region is longitudinally extended along the longitudinal direction of the binding strap, and accordingly, the distance defined between the gripped portions of the strap 3 and the strap end portions 3a and 3b being bonded together by means of the seal fitment 7 or the like is increased as a direct function of the increased longitudinal extent of the the jaw portion 8 and the multiple-toothed cutter 5. Consequently, upon removal of the jaw portions 6 and 8 from beneath the bonded strap portions, substantial looseness or slack is developed or generated within the bound binding strap whereby the residual tension present within the binding strap is substantially decreased. Consequently, the use of such a multiple-gripping means when binding coil-like or small-sized articles is not practical since the aforenoted decrease in residual tension is disproportionately high. In addition, it is noted that the plurality of gripping locations must be equally arranged and that the gripping conditions attendant thereto be equalized. Consequently, abnormal free spaces, in the thickness direction of the binding strap, must be eliminated, and this objective requires precise adjustment or disposition of the strap portion to be gripped. Lastly, in view of the fact that such gripping means are longitudinally extended along the longitudinal direction of the binding strap, the size of the binding head is increased in size relative to, for example, a binding head employing a single-gripping means.